New Zealand Scholarship · Physics and Chemistry

Chemical Equilibrium, Thermodynamics, Electrochemistry and Spectroscopy

35 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 35 questions

  1. In 1H NMR spectroscopy, what splitting pattern is observed for the hydrogen atoms on the -CH2- carbon of pure bromoethane (CH3-CH2-Br)?
  2. What is the pH of a 0.050 mol/L aqueous solution of barium hydroxide, Ba(OH)2, at 25 degrees Celsius?
  3. According to Le Chatelier's principle, how does increasing total pressure at constant temperature affect the Haber equilibrium: N2(g) + 3 H2(g) <=> 2 NH3(g)?
  4. For an electrochemical cell with standard potential E_cell^0 = +1.10 V at 298 K, what is the sign and meaning of standard Gibbs free energy change Delta G^0?
  5. What is the solubility product expression K_sp for sparingly soluble silver phosphate, Ag3PO4?
  6. What prominent absorption band in an infrared (IR) spectrum confirms the presence of a carboxylic acid -O-H group?
  7. Under what conditions is a chemical reaction always thermodynamically spontaneous at all temperatures?
  8. What is the conjugate base of the dihydrogen phosphate ion, H2PO4^-?
  9. What is the molar solubility s of calcium fluoride, CaF2, in water if its solubility product is K_sp?
  10. How does adding a non-volatile solute like sucrose affect the boiling point and freezing point of water?
  11. What is the oxidation state of chromium in the dichromate ion, Cr2O7^2-?
  12. What determines whether a buffer solution of ethanoic acid (CH3COOH) and sodium ethanoate (CH3COONa) resists changes in pH when strong acid is added?
  13. According to the second law of thermodynamics, what must be true for any spontaneous process in an isolated system?
  14. What is the standard cell potential for a Daniell cell: Zn(s) | Zn^2+(aq, 1M) || Cu^2+(aq, 1M) | Cu(s)? (E^0(Zn2+/Zn) = -0.76 V, E^0(Cu2+/Cu) = +0.34 V)
  15. What type of organic reaction occurs when 2-bromobutane is treated with hot concentrated ethanolic KOH?
  16. What relationship connects the standard equilibrium constant K to standard Gibbs free energy change Delta G^0 at temperature T?
  17. In mass spectrometry of organic molecules, what produces the [M+2] peak with approximately one-third the intensity of the molecular ion peak [M]^+?
  18. What is the function of a salt bridge in a galvanic electrochemical cell?
  19. Why is ethanoic acid (pK_a = 4.76) a significantly stronger acid than ethanol (pK_a ~ 16)?
  20. What is Hess's Law of Constant Heat Summation and what property of enthalpy does it reflect?
  21. What is the pH of a buffer solution prepared from 0.20 mol/L ethanoic acid and 0.20 mol/L sodium ethanoate (pK_a = 4.76)?
  22. Which of the following molecules has a non-zero net dipole moment (is polar)?
  23. What happens to the equilibrium constant K_c for an endothermic reaction (Delta H > 0) when temperature is raised?
  24. In an electrolytic cell, at which electrode does reduction occur and what is the electrical polarity of that electrode?
  25. What is the order of reaction with respect to reactant A if doubling [A] while keeping other concentrations constant quadruples the initial reaction rate?
  26. Which transition metal ion in aqueous solution is colourless due to having a completely filled d-subshell (d10 configuration)?
  27. What is the standard enthalpy of combustion of a fuel defined as?
  28. Why is the boiling point of water (H2O, 100 deg C) drastically higher than that of hydrogen sulfide (H2S, -60 deg C)?
  29. What is the rate-determining step in a multi-step chemical reaction mechanism?
  30. What is the entropy change Delta S_surr of the surroundings when an exothermic reaction releases heat q_sys at temperature T?
  31. What optical technique measures the rotation of plane-polarized light to distinguish between chiral enantiomers?
  32. What is the conjugate acid of ammonia, NH3?
  33. What is the hybridization and molecular geometry of sulfur hexafluoride, SF6?
  34. Which of the following processes represents an increase in standard entropy (Delta S > 0)?
  35. What is the role of an enzyme or chemical catalyst in a chemical reaction?

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